When news broke that Rep. Paul Ryan (Wis.) had been tapped as presumptive GOP presidential nominee Mitt Romney's running mate, many of his colleagues on Capitol Hill turned to Twitter to share their reactions. In the process, they may have unwittingly violated House and Senate rules that prohibit Members from "campaigning" via tweets.

The Sunlight Foundation, which collects politicians' deleted tweets and posts them online, found a number of instances where Congressional lawmakers, primarily from the House side, expressed excitement or disappointment over the Ryan pick - and then erased them from their Twitter feeds.

"Could NOT be more thrilled with the @RepPaulRyan VP pick. Romney-Ryan 2012!!" tweeted Rep. Jeb Hensarling (R-Texas), who took the post down after 44 seconds.

"@Matt_Romney Saw you on TV Sat. standing next to our outstanding VP pick, Paul Ryan. Thanks for making the trip to Spokane last week. #VP," Rep. Cathy McMorris Rodgers (R-Wash.) wrote to Romney's son, keeping the tweet online for 21 hours.

"@MittRomney sent a clear msg to Independent voters this a.m.: 'Take a hike,'" tweeted Rep. Chris Van Hollen (D-Md.), ranking member on the Budget Committee to Ryan's chairman. He deleted the statement 37 minutes later.

These tweets might have been deleted, the Sunlight Foundation suggested in a blog post Wednesday, because the lawmakers or their offices realized they were running afoul of policies that ban them from electioneering through social media accounts maintained in their official capacity as sitting Members of Congress.

"The tweets that the Sunlight Foundation report referenced ... I think there is a reason why they were deleted," a House aide familiar with the rules regarding franking and mass communications told Roll Call. "Someone maybe had second thoughts or decided it wasn't an appropriate use of official resources, and they were deleted."

Rep. Renee Ellmers (R-N.C.) tweeted a series of congratulatory and celebratory messages about the Ryan pick, all of which have since been deleted.

"I applaud the great VP choice @MittRomney made in principled conservative and American success story @RepPaulRyan," one such tweet read.

The Sunlight Foundation reported that Ellmers' spokesman, Tom Doheny, confirmed that the staff recognized quickly that the tweets were out of bounds, typed out in the "heat of the moment" and "mistakenly sent out on the official account."

As Twitter use has expanded, lawmakers have struggled to nail down and then conform to specific rules and regulations regarding their behavior. Finding common ground over what constitutes its appropriate use is further complicated by the fact that Members' Twitter accounts, like other social networking tools, are managed at any given moment in time by full-time staffers, part-time interns and the Members themselves.

"It was yet another indication that lawmakers, who are working hard to be hip to social media, haven't quite mastered the nuances of communications in an electronic age," the Sunlight Foundation's Kathryn Lucero wrote of these recent incidents. "Social media has helped congressional offices connect with constituents. ... But the easy access to these new media platforms, like Twitter, has led many elected officials to impulsively blurt out their opinion regarding campaign-related matters."

The Members' Congressional Handbook governs posting standards on third-party social media sites for Members in the House and is very specific in its ban on electioneering on those sites in official capacities - but does not mention Twitter specifically. A new franking manual could be rolled out later this year from the bipartisan House Franking Commission that revises and clarifies terms of use across a wide range of Members' mass communications, but Twitter rules would not be included in that update.

Correction: 10:15 a.m.

An earlier version of this article incorrectly stated what would be included in the new franking manual. The Members' Congressional Handbook dictates terms of use for Twitter and the use of third-party social media websites.